#BFDCEC

CSS

:root {
  --sleepless-blue: #bfdcec;
  --sleepless-blue-rgb: 191 220 236;
  --sleepless-blue-oklch: oklch(0.878 0.038 232);
}

.element {
  color: var(--sleepless-blue);
  background-color: hsl(201 54% 84%);
  border-color: oklch(0.878 0.038 232);
}

Tailwind CSS v4

@theme {
  --color-sleepless-blue: #bfdcec;
  --color-sleepless-blue-50: #ebf7ff;
  --color-sleepless-blue-100: #dceaf3;
  --color-sleepless-blue-200: #c5d7e2;
  --color-sleepless-blue-300: #a5bbc8;
  --color-sleepless-blue-400: #89a3b1;
  --color-sleepless-blue-500: #6d8b9b;
  --color-sleepless-blue-600: #5d7683;
  --color-sleepless-blue-700: #4a5e69;
  --color-sleepless-blue-800: #35454d;
  --color-sleepless-blue-900: #243036;
  --color-sleepless-blue-950: #131c21;
}

SCSS

$sleepless-blue: #bfdcec;
$sleepless-blue-rgb: 191, 220, 236;
$sleepless-blue-light: mix(#fff, $sleepless-blue, 20%);
$sleepless-blue-dark: mix(#000, $sleepless-blue, 20%);

.element {
  color: $sleepless-blue;
  box-shadow: 0 0 0 2px rgba($sleepless-blue, 0.35);
}